We report two patients with reversible cerebral vasoconstriction syndrome (RCVS) and carotid glomus tumour. The first patient presented with multiple thunderclap headaches. Cervical and cerebral magnetic resonance imaging showed diffuse cerebral vasoconstriction on magnetic resonance angiogram (MRA) and a carotid glomus tumour. The second patient presented with a cervical mass and was diagnosed with a non-secreting paraganglioma of the carotid body. Surgery with pre-operative angiography was followed by thunderclap headaches and MRA showed segmental cerebral vasoconstriction. Both patients were treated with nimodipine and headaches stopped. Both had normal cerebral arteries on the control MRA at 3 months. These two cases suggest that a paraganglioma may increase the susceptibility to develop RCVS. As a consequence, patients with RCVS should be investigated for a carotid glomus tumour, and patients with paraganglioma reporting severe headaches should have a cerebral MRA in order to rule out cerebral vasoconstriction.